Pressure induced ventricular hypertrophy is associated with a 20-40 percent decrease in capillary density in the myocardium. The physiological significance of this observation is largely unknown. Preliminary studies in my laboratory have shown that coronary vascular resistance is increased in resting awake hypertensive dogs with pressure induced ventricular hypertrophy. Furthermore, following maximal coronary vasodilatation with adenosine, coronary vascular resistance in dogs with pressure induced ventricular hypertrophy is greater than in normal animals. To explore the potential abnormalities in myocardial perfusion that occur as a result of pressure induced ventricular hypertrophy studies will be directed at three goals; 1. To study regional capillary density (epicardium/mid-wall/endocardium) in hypertrophied myocardium. 2. To study the effects of stress (treadmill exercise; reactive hyperemia) on total and regional coronary blood flow of hypertrophied myocardium. 3. To assess the relationship between coronary flow and myocardial metabolic demands in the stressed hypertrophied myocardium. In these studies regional perfusion and metabolism (lactate and pyruvate concentrations in different layers of the stressed hypertrophied myocardium) will be measured. These studies will expand our knowledge of the effects of pressure induced ventricular hypertrophy on the coronary circulation. Since pressure induced ventricular hypertrophy secondary to hypertension is common in patients with coronary disease, increased knowledge in this area is needed.